1. Field of the Invention
The present invention relates to a CMOS image sensor, and more particularly, to a CMOS image sensor capable of improving low exposure and high exposure qualities of image and a manufacturing method thereof.
2. Description of the Related Art
Recently, CCD or CMOS type image sensors have been developed by companies, such as Omnivision, Micron, Foveon, Sony, Samsung Electrionics, Dongbu hightec, Magnachip, etc.
The former CCD type image sensor has been developed by a Long Electron Life Time technology, a Double poly technology, and a High Voltage semiconductor technology. The CCD image sensor can be manufactured using only three to four parts and provides excellent image quality. However, the CCD type image sensor requires driving powers of different levels 14 V, 3.3 V, −8 V and consumes power three times as much as the CMOS image sensor.
The latter CMOS image sensor has been mainly used for a cellular phone camera, a digital still camera, etc. Although CMOS image sensor has advantages, such as compact size, low power consumption, single chip, high integration, and high pixel, the low exposure sensitivity deteriorates with the increase of dense, which should be improved.